Over the past 30 years, California has spent an increasing portion of its budget on prisons — and a shrinking share on the University of California and California State University systems.

As the state’s budget has tightened, school districts across California have faced the difficult task of balancing classroom spending with ballooning costs for maintenance, energy bills and a raft of other costs.

Half of the Bay Area’s 10 largest school districts spent less than the statewide average of 62 percent of their general funds on direct classroom instruction costs in the 2009-10 school year, according to the most recent figures available from the state Department of Education. They include the San Francisco Unified, Oakland Unified, San Jose Unified, West Contra Costa and the East Side Union High School districts.

Classroom spending accounted for 53 percent of the Oakland Unified School District’s general fund budget in 2009-10, down from 59 percent of the general fund in the 2003-04, school year, according to California Department of Education figures. San Jose Unified allocated 57 percent of its general fund to direct instruction costs in the 2009-10 school year, compared to 60 percent seven years earlier.

Among the districts that spent the smallest share of their budget on the classroom in the 2009-10 school year were Oakland Unified, which spent 54 percent, and San Francisco Unified, which allocated 47 percent.

State funding for public school districts steadily grew between the 2003-04 school year and the 2008-09 school year, when funding was cut. It has remained relatively flat since the 2008-09 school year.

The budget for the California Department of Corrections and Rehabilitation increased from about 3 percent of the state's general fund in 1980 to 11.2 percent for this fiscal year, according to figures prepared at the request of The Bay Citizen by the state Department of Finance. Meanwhile, funding for UC and CSU dropped from 10 percent of the state's general fund 30 years ago to about 6.6 percent this fiscal year.

Nationwide, state spending for criminal corrections has boomed. According to an April 2011 study by the Pew Center on the States, spending for corrections quadrupled over the last two decades, making it the second fastest growing area of state budgets, behind Medicaid. In California, spending for criminal corrections has more than tripled since 1980.

The state's prison population has increased significantly over the last 30 years, largely because the state began imposing determinant sentences, meaning the vast majority of crimes have fixed prison terms. Compounding the problem is the state's three strikes law, established in 1995. The number of prisoners climbed from about 25,000 in 1980 to about 165,000 in 2010. About two-thirds of the people who enter the state's prisons each year are offenders who have violated the terms of their parole. The state spends about $50,000 per inmate each year.

The reasons for the mounting prison costs are complex, according to Barry Krisberg, director of research and policy at the Chief Justice Earl Warren Institute on Law and Social Policy at University of California, Berkeley, School of Law.

"The growth in spending for pay and benefits for prison guards, prison health care mandated by various lawsuits, and the extraordinary amounts of money we are paying prison doctors" all contribute, he said. "California is clearly the worst in the U.S. for what we get and what we spend. California has the largest prison system in the U.S., it is the most expensive per capita rate in the U.S. and the state has some of the highest recidivism rates of any state in the nation."

In raw numbers, spending on both corrections and higher education has increased since the 1980s. In fiscal year 1979, the state spent about $1.9 billion on higher education, while the corrections budget totaled $625.4 million. This year, the UC and CSU systems are receiving $5.7 billion, while prisons account for $9.6 billion in state spending.

However, the state has imposed deep cuts to higher education in recent years. Spending on higher education peaked in fiscal year 2007 at $7.4 billion and has decreased nearly every year since then.